An axial air gap rotating electric machine has a configuration in which a substantially donut-shaped stator and a disk-shaped rotator are disposed to face each other in a rotation axis direction. The stator includes multiple core members for a single slot disposed in an annular shape in a diameter direction around a rotation axis. The core member includes an iron core, a tube-shaped bobbin (insulator) into which the iron core is inserted, a coil wound around an outer periphery of the bobbin, and the like. Since a gap surface generating a torque increases substantially in proportional to a square of a diameter, the axial air gap rotating electric machine is considered to be suitable for a thin shape. In recent years, this attracts attention as a structure useful for reducing the size and increasing the efficiency in rotating electric machines required to be made into a thin shape.
In general, in order to reduce the size and increase the efficiency of rotating electric machines, it is important to arrange the iron core and armature coils directly contributing to the torque output with a higher density within the stator. The iron core forms a magnetic circuit of the rotating electric machine, and when the iron core is formed to have a low magnetic resistance with respect to the main magnetic flux, a magnetic flux generated by coils and permanent magnets can be effectively used. The armature coil is the source of the magnetomotive force, and in a case where the same number of turns is assumed, the armature coil is formed to increase this volume, so that the wire diameter is expanded, and accordingly, the joule loss in the coil can be reduced, i.e., the efficiency of the rotating electric machine can be enhanced.
In the axial air gap rotating electric machine, an increase in the density of iron cores and coils is an important technical problem, and in the past many inventions have been made.
Patent Literature 1 discloses a method for winding a coil in an axial air gap rotating electric machine and a method for producing a coil. In this case, a coil is wound around a predetermined shaft having a predetermined width, and a method for directly winding a coil around an iron core having a flange portion and a method for winding a wire around a bobbin having a flange portion are shown. Patent Literature 2 discloses a method for directly connecting bobbins in the axial direction while the iron core is inserted into the inside of the bobbin, and the wire is continuously wound around the bobbin.
At the side where the coil is applied, i.e., at the bobbin and the iron core, some tightening force is applied to deform it. For this reason, it is easier to insert a core into a bobbin when the coil is applied to the bobbin while the iron core is inserted thereto. Further, when a coil is turned and wound, the winding bulge can be suppressed by applying tension to the coil, so that the coil can be wound with a higher density. In this case, however, a large force is also applied to the winding shaft which holds the coil, and therefore, it is necessary to rigidly hold the core member.